Setback Control Supplement
Determine the Setback Schedule
Use the following steps to define the schedule necessary to optimize the Setback Control for solar
thermal use. Once the schedule is determined, the Setback Control can be programmed according
to the Setback Control Installation and Operation Manual.
The Setback Control has four customizable periods per day. The water temperature setpoint and
time can be set for each of the following periods: Wake, Leave, Return and Sleep. A Reference
Time / Water Temperature chart is included in the Setback Control Installation and Operation
Manual to record the chosen values.
The Setback Control maximum water temperatures are limited to the maximum temperature
setting on the gas control.
NOTICE
Wake:
Determine the earliest time in the day that a substantial amount of hot water would be used. Take
into consideration larger hot water usage such as showers, baths, washing dishes and laundry.
Subract one hour and use as the Wake time. The water temperature setting must be at a safe level
for household use.
It is recommended that the Leave and Arrive times be updated for the upcoming season (winter
or summer) at Daylight Savings Time, if applicable
NOTICE
.
Leave:
In the continental United States, it is recommended to use 9:30 AM for winter and 8:30 AM for the
summer Leave times. If a more location specific time is desired, determine the local average
sunrise time for the upcoming season. Add two hours to allow for sunrise variation in the season
and for the sun to reach an appropriate angle to provide usable heat. The water temperature
should be set low enough to optimize solar heat transfer while still providing the minimum amount
of hot water backup in the event of unfavorable weather conditions.
Return:
In the continental United States, it is recommended to use 3:30 PM for winter and 4:30 PM for the
summer Return times. If a more location specific time is desired, determine the local average
sunset time for the upcoming season. Subtract two hours to allow for sunset variation in the
season. When close to sunset, the sun is not at an appropriate angle to provide usable heat. The
water temperature setting must be at a safe level for household use.
Sleep:
Determine the latest time in the day that a substantial amount of hot water would be used and use
as the Sleep time. The water temperature setting should be set back to reduce standby losses.
Example Schedule:
The Setback Control scheduled times and temperatures will vary from household to household,
depending on location and activities. The example below represents waking at 6:30 AM to shower,
the dishwasher started at 8:00 PM and children’s baths at approximately 8:30 PM. The installed
ASSE mixing valve is adjusted to provide a safe maximum outlet water temperature.
Wake Leave Return Sleep
Season
Time Temperature Time Temperature Time Temperature Time Temperature
Winter
5:30AM 125°F 9:30AM 90°F 3:30PM 125°F 9:00PM 85°F
Summer
5:30AM 120°F 8:30AM 90°F 4:30PM 120°F 9:00PM 85°F